IEEE 802.11 is a set of standards for implementing wireless local area network (WLAN). In IEEE 802.11 physical (PHY) layer frame format, the preamble part is usually composed of three fields: a short training field (STF), a long training field (LTF), and a signal field (SIG). The STF is used for coarse synchronization, automatic gain control (AGC), and the like. The LTF is used for channel estimation, fine synchronization, etc. The SIG is used to indicate the information of the frame; rate, length, and the like. As IEEE 802.11 WLAN technology evolves, a preamble design for IEEE 802.11ah is needed for its own network environment.